This invention is concerned with a supporting mechanism for supporting mould side portions in a glassware forming machine, e.g. of the individual section type.
In glassware forming machines of the individual section type, the supporting mechanisms for the mould side portions comprise two arms each arranged, on the application of a mould closure force thereto, to move in predetermined directions from mould open positions thereof to mould closed positions thereof and to remain in the mould closed positions during a moulding operation of the machine. In some machines of the individual section type, the arms move towards one another arcuately about a common vertical axis to reach their mould closed positions whereas in other machines he arms move linearly towards one another. In the mould closed position, one or more mould side portions (there may be as many as four) supported on each arm cooperate with mould side portions supported on the other arm to define mould cavities in which molten glass can be moulded. On the application of a mould opening force, the arms return to their mould open positions, by moving in the opposite direction to said predetermined direction. In their mould open positions, the mould side portions supported on each arm are separated from those supported on the other arm to allow removal of moulded glass. Such supporting mechanisms are used both for "blank" moulds for moulding gobs of molten glass into parisons, by a pressing or a blowing operation, and also for "finish" moulds for moulding parisons into completed articles of glassware.
Conventionally, the supporting mechanisms comprise an upper and a lower support mounted on each arm. The upper and lower support on an arm cooperate in supporting said one or more mould side portions. The supports are generally mounted on the arm for limited pivoting movement and each defines a recess into which a hook-shaped projection of the mould side portion extends so that the mould side portion hangs on the supports. Normally, a mould side portion rests on the upper support while the lower support prevents the mould side portion from pivoting relative to the upper support.
In conventional supporting mechanisms, problems can arise due to poor distribution of the mould closure force between the upper and lower supports so that one support may apply excessive or insufficient force to part of the mould side portion. This can result in the formation of pronounced seams on the parison or bottle. In the case of bottles with long necks and a large body diameter, the lower part of mould is often forced further open by the air pressure used to mould the glass. In the case of the blank moulds in a narrow neck press and blow operation, the lower part of the mould also tends to be forced open by the plunger used for the pressing operation. Suggestions for alleviating these problems are described in U.S. Pat. Nos. 3,967,946 and 4,101,306. In U.S. Pat. No. 3,967,946, a supporting mechanism is described which incorporates a hydraulic system having two pistons pressing against the mould side portion, one against an upper part and the other against a lower part. The cylinders in which the pistons move are interconnected by a pipe containing hydraulic fluid so that, when the one piston is pressed inwardly by the mould side portion, the other piston exerts pressure thereon. This mechanism is relatively complex and is not, as far as is known, is use. In U.S. Pat. No. 4,101,306, a supporting mechanism is described in which the upper and lower supports are integral and can tilt about a horizontal axis. The lower support is also unconventional in that it has a projection extending downwardly into a recess in the mould side portion, thus making mould changing move complex. This mechanism is also relatively complex and would lead to variations in the height of the mould as the supports pivoted.
It is an object of the present invention to provide a supporting mechanism of the type referred to in which the aforementioned problems are avoided and which avoids the disadvantages of the aforementioned suggestions.